How to preserve the timeless beauty of Oamaru Stone

Spring is a time of renewal, and that goes for Oamaru Stone too. Oamaru Stone responds brilliantly to just a small amount of attention, and now is a great time to do it – we’ll at least once we start seeing some drier weather.

From the classic ornate Victorian buildings in downtown Oamaru to the latest architectural masterpieces featured on Archipro, Oamaru Stone has a timeless beauty all of its own. Its rich honey tones and the ability of limestone to be easily shaped and sculpted make it a unique building material.

But like everything, it benefits from care and maintenance. To help keep your Oamaru Stonework looking at its best and proudly standing the test of time, we have some simple ‘spring cleaning’ hints and tips.

Today we’ll cover:

Preparation and waterproofing of new builds constructed using Oamaru Stone
Resealing and maintenance of existing Oamaru Stone buildings

Preparation and waterproofing of newly constructed Oamaru Stone buildings

When the building is complete and the site has been cleaned up, the final step is preparing the exposed Oamaru Stone for its water-repellent sealer.

Aquellux S and RTS No.4

We highly recommend the use of these great New Zealand products, Aquellux S and RTS No.4, on all Oamaru stone structures. These are state-of-the-art siloxane & polysiloxane water repellents which are used to make porous building materials water repellent without changing their appearance.

Note: It’s very important to act as soon as you notice any discolouration on Oamaru Stone surfaces to kill the organic growth, even if the stone can’t be sealed until summer.

Start by washing all the surfaces to remove any marks from the building process; in most cases, a soft-bristle brush and water will do the trick.

Any areas that are discoloured by moss or mould should be treated with a moss and mould killer, Hypostat and Moss Kill mixed 50:1 is what we recommend. Simply spray it onto the surface and let it do its work over 24-48 hours, then wash the stone with a hose (repeat the process if necessary). Applying the sealer essentially locks in the stone’s appearance, so it is important you are happy with it before doing so. The stone needs to be as dry as possible; it’s for this reason that we don’t recommend sealing stone in winter. Simply apply the Hypostat/Moss Kill solution and wait for more favourable weather. When it’s dry and the weather is settled, it’s time to apply the water repellent silicone sealer.

You’ll need to apply your water repellent at the rate of approximately 1 litre per 1-1.5 m2.

Please get in touch with us for professionals who can do the sealing in your area or instructions on applying the sealer to the stone.

And you’re all done! Under normal circumstances, properly treated Oamaru Stone surfaces will stay water-resistant for up to 10 years.

Resealing and maintenance of existing Oamaru Stone buildings

If your building is a few years old, the first step is to check if your Oamaru Stone needs resealing.

Spray a little water onto the stone surface, and if the water repellent sealant is still working, the water will create droplets on the surface.

On the other hand, if the surface has become porous due to degradation of the water repellent coating, the water will be absorbed. You can tell if absorption is occurring if the stone turns slightly darker when it’s wet.

Another very obvious clue that Oamaru Stone is in urgent need of treatment is when you have mould, moss or lichen growing on the surface, which, as we noted above, must be dealt with immediately

To clean the stone, we recommend the use of Hypostat and Moss Kill 50:1 applied liberally so that the surface is thoroughly wetted. Leave the product to work for over 24/48 hrs, then wash off stubborn areas that may need to be agitated with a firm-bristle nylon brush. In some areas where there is a strong build-up of moss or mould, a wire brush might be needed to give it a really good clean. We would recommend professional assistance with this process so your stone isn’t damaged.

But whatever you do, DO NOT under any circumstances use a pressure washer or water blaster to clean Oamaru Stone surfaces, as they can loosen the pointing and permanently damage the stone.

This is also the time to do any repairs, for example, replacing loose pointing. Then once the stone has completely dried, and you are happy with the stone’s appearance, apply Aquellux S or RTS No.4, water repellent sealer as above, remembering that Oamaru Stone requires the sealer to be applied at a higher rate than concrete, as it’s more porous.

The enduring beauty of Oamaru Stone

Oamaru Stone requires just a minimum level of maintenance, which, if it’s done according to these guidelines, will reward you with beauty and substance that will last for centuries.

If you’re inspired by the possibilities of working with Oamaru Stone for your next building project, give us a call today on 03 433 1134 or email sales@oamarustone.co.nz.